Multi-SIM (subscriber identification module) wireless devices have become increasing popular because of their flexibility in service options and other features.
In various types of multi-SIM wireless communication devices, each modem stack associated with a subscription may store information provisioned by a respective network operator in a SIM, which may allow the SIM to support use of various different communication services. For example, various wireless networks may be configured to handle different types of data, use different communication modes, implement different radio access technologies, etc. One type of multi-SIM wireless device, referred to as a dual-SIM dual-active (DSDA) device, is typically configured with separate transmit/receive chains associated with each SIM, thereby allowing simultaneous active connections with the networks corresponding to two SIMs. Some DSDA devices, referred to as single-transmit DSDA devices, are configured with separate receive chains associated with each SIM, but a single shared transmit chain. The single-transmit configuration reduces hardware costs and power requirements of the wireless communication device.
In both DSDA device configurations, potential conflicts between activities on the separate RF resources may arise during simultaneous communications. For example, the transmit circuitry associated with one SIM may cause desense to the receive circuitry associated with another SIM based on their coexistence and proximity within the same device. In another example, in a single-transmit DSDA device, timing collisions may arise between transmissions. To mitigate these conflict scenarios, a DSDA device may stop the lower priority communication by blanking transmissions in the uplink. For example, in simultaneous communication activities on a Long Term Evolution (LTE) network and a GSM network, the GSM communication activity (e.g., a voice call) is typically allocated the higher priority, with LTE uplink blanking. While blanking LTE transmissions at a symbol level may always provide better throughput on the downlink, in the uplink the better throughput result depends on whether a base station (i.e., eNodeB) is capable of discontinuous transmission (DTX) detection (i.e., differentiating sub-frames that were not received due to link failure versus due to DTX). However, there is no convenient mechanism by which a DSDA device may determine whether a particular base station/eNodeB is capable of DTX detection to guide this switching.